Electric fan

ABSTRACT

An electric fan comprises a blade impeller and an electric motor with a rotor part including a plurality of permanent magnets fixed to a peripheral ring of the impeller, and a stator part which faces a portion of the said ring of magnets of the rotor and which comprises a winding and a support structure in which the impeller is rotatably mounted and to which the stator part of the motor is fixed.  
     The support structure comprises a bracket of generally elongate form having a first end provided with rotation support means for the impeller and a second end to which the stator part of the electric motor is fixed.

DESCRIPTION

[0001] The present invention relates to an electric fan usable, forexample, for cooling a heat exchanger such as a radiator associated withthe internal combustion engine of a motor vehicle.

[0002] More specifically, the subject of the invention is an electricfan of the type comprising a blade impeller and an associated electricmotor including a rotor part comprising a ring of permanent magnetsfixed to a peripheral ring of the impeller, and a stator part whichfaces a portion of the said ring of magnets of the impeller and whichincludes a winding and a support structure in which the impeller isrotatably mounted and to which the said stator part of the motor isfixed.

[0003] The object of the present invention is to provide an electric fanof the above-specified type, which has a particularly simple structurewhich can be assembled and installed in a simple and economic manner.

[0004] This and other objects are achieved according to the inventionwith an electric fan of the above-specified type, characterised in thatthe said support structure comprises a bracket of generally elongateform having a first end provided with means for supporting rotation ofthe impeller and a second end to which the said stator part of theelectric motor is fixed.

[0005] In a preferred embodiment of the invention a receptacle is formedin the said second end of the bracket, which can receive control circuitmeans coupled to the stator part of the electric motor. Advantageouslythe bracket is made of a metal material such as aluminium, and is inheat exchange relation with at least some components of the said circuitmeans in order to encourage the dissipation of heat.

[0006] According to a further advantageous characteristic of theinvention the winding of the stator part is made with stacks oflaminations of electrically conductive material such as copper or itsalloys, carried by a support plate which also carries connectionconductors for interconnecting them.

[0007] Further characteristics and advantages of the electric fanaccording to the invention will become apparent from the followingdetailed description given purely by way of non-limitative example, withreference to the attached drawings, in which:

[0008]FIG. 1 is a partly exploded perspective view of an electric fanaccording to the invention;

[0009]FIG. 2 is an axially sectioned partial view of a peripheralportion of the impeller of the electric fan of the invention;

[0010]FIG. 3 is an axially sectioned partial view of the hub of theimpeller;

[0011]FIG. 4 is a perspective view of a support bracket of the electricfan;

[0012]FIG. 5 is a perspective view of a variant embodiment of thesupport bracket;

[0013]FIG. 6 is a perspective view which shows the bracket of FIG. 5 inassociation with an air conveying support structure for the electricfan;

[0014]FIGS. 7 and 8 are sectioned views taken on the lines VII-VII andVIII-VIII respectively of FIG. 5;

[0015]FIG. 9 is a partial perspective view which shows a particular wayof making the stator part of an electric fan according to the invention;

[0016]FIG. 10 is a perspective view, on an enlarged scale, of a detailseen from the direction of the arrow X of FIG. 9; and

[0017]FIG. 11 is a perspective view which shows the detail of FIG. 10seen from the direction of the arrow XI of this Figure.

[0018] With reference to FIG. 1, an electric fan 1 according to theinvention comprises a support casing 2 in which there is defined anessentially circular passage 3. At the exit from this passage, that isto say essentially on the rear side of the support body 2, extends asupport ring 4 interconnected with the body 2 by means of a series ofspokes 5.

[0019] The electric fan 1 comprises an impeller generally indicated 6,having a hub 7 from which extends a ring of arcuate blades 8. The outerends of these blades are joined to a peripheral ring 9.

[0020] Conveniently, according to a technique already known per se, thehub 7, the blades 8 and the peripheral ring 9 of the impeller are madein one piece of moulded plastics material.

[0021] In FIGS. 1 and 2 the reference numeral 10 indicates a metal ringon the outer surface of which is fixed, for example by adhesive, a ring11 of permanent magnets 12.

[0022] As seen in FIG. 2, the ring 2 and the ring 11 formed by themagnets 12 are embedded in the peripheral ring 9 of the bladed impeller6 upon moulding of this latter, in such a way that the rotor part of themotor associated with this impeller is practically integral with it.

[0023] As seen in FIG. 3, a tubular metal insert 13 is convenientlyembedded, upon moulding, in the hub 7 of the impeller 6, at the ends ofwhich are defined two seats 14 and 15 of greater diameter to allowrespective bearing supports 16 and 17 (FIG. 1) to be fitted to them.

[0024] The electric fan 1 further includes a support bracket generallyindicated 20 in FIG. 1 and 4.

[0025] This support bracket 20 is conveniently made of metal such asaluminium or its alloys. It has a generally elongate form and one end 20a thereof carries a pin 21 which is inserted into the bearing support 16and 17 of the impeller 6 to act as a fixed shaft for the rotation ofthis latter.

[0026] The end 20 a of the bracket 20 further has three holes for thepassage of screws which, being engaged in corresponding holes of thering 4 of the support body 2, contribute to the fixing of the bracket 20to this body.

[0027] The other end 20 b of the bracket 20 forms a receptacle 23 inwhich is conveniently housed a circuit board (not illustrated) carryingthe control circuit components associated with the motor of the electricfan. In particular at least some of these components, in the mountedcondition, are in heat exchange relationship with the bracket 20 whichtherefore also acts as a dissipater for heat developed in operation ofthese components.

[0028] The end portion 20 b of the bracket 20 has a pair of throughholes 24 (only one of which is visible in FIG. 4) for the passage ofcorresponding fixing screws which allow this end of the bracket 20 alsoto be fixed to the support body 2. Adjacent the receptacle 23 defined inthe bracket 20 there is fixed to this latter a terminal block of 25 ofelectrically insulating material from which extend terminals 26 whichare intended to be connected to the circuits housed in the saidreceptacle, and a plurality of electrical terminals 27 intended forconnection of the windings of the stator part of the motor of theelectric fan.

[0029] The stator part comprises a stack of stator laminations 28 in theform of arcuate segments, forming a plurality of teeth 29 alternatingwith recesses 30. Around these teeth and in the said recesses are woundconductors which form the winding 31 (FIG. 1) of the stator part.

[0030] The stack of stator laminations 28 and the terminal block 25 areconveniently fixed to the bracket 20 by means of the same pair ofscrews.

[0031] In the embodiment illustrated in FIGS. 1 and 4 the intermediateportion of the support bracket 20 has a plurality of longitudinal slots32 intended to allow the passage of air which in operation is blown bythe impeller 20 into the passage 3 of the support body 2.

[0032] A variant embodiment of the support bracket 20 will now bedescribed with reference to FIGS. from 5 to 8. In these Figures theparts and elements which are the same as or essentially equivalent toparts and elements already described have been again allocated the samereference numerals.

[0033] In the variant illustrated in particular in FIG. 5 theintermediate portion of the support bracket 20 forms a plurality ofangularly spaced deflector elements or flow straighteners 40. A similarseries of deflector elements or flow straighteners indicated 41 in FIG.6 extend from the support ring 4 to the outlet of the conveyor duct 3.The deflectors or flow straighteners 41 form an angularly complementaryassembly to that formed by the deflectors or flow straighteners 40 ofthe support bracket 20. In other words, when the bracket 20 is mountedin position on the body 2 its deflectors or flow straighteners 40combine with the deflectors or flow straighteners 41 to form, overall, aring of angularly equally spaced deflectors or straighteners.

[0034] As is shown in FIGS. 7 and 8, each deflector or flow straightener40 has in its radially innermost region an essentially straight crosssection as shown in FIG. 7, which progressively curves in the directionof its radially outer portion in correspondence with which, as seen inFIG. 8, its cross section has an accentuated curvature. The same isobviously true for the flow straighteners 41 of the support body 2.

[0035] For the rest, the support bracket 20 essentially corresponds tothat previously described with reference to FIGS. 1 and 4.

[0036] In general, in an electric fan of the type described above, thewinding of the stator part of the electric motor must be made withconductors having a large cross section for the purpose of ensuring ahigh performance. However, the formation of windings with conductors oflarge cross section is a complicated operation.

[0037] The problems connected with the winding of wires of large crosssection can be avoided with the arrangement which will now be describedwith a reference to FIGS. from 9 to 11.

[0038] These Figures illustrate portions of the stator part of the motorassociated with the electric fan, in which the winding 31 is made withstacks 50 of laminations 51 of electrically conductive material such ascopper or its alloys, carried by a support plate 52 of electricallyinsulating material which carries connection conductors 53 forinterconnecting them (FIG. 11).

[0039] Naturally, the principle of the invention remaining the same, theembodiments and details of construction can be widely varied withrespect to what has been described and illustrated purely by way ofnon-limitative example, without by this departing from the ambit of theinvention as defined in the attached claims.

What is claimed is:
 1. An electric fan comprising a blade impeller andan associated electric drive motor including a rotor part comprising aplurality of permanent magnets fixed to a peripheral ring of theimpeller, and a stator part which faces a portion of the said ring ofmagnets of the rotor and which includes a winding and a supportstructure in which the impeller is rotatably mounted and to which thesaid stator part of the motor is fixed; the electric fan beingcharacterised in that the said support structure comprises bracket ofgenerally elongate shape having a first end provided with rotationsupport means for the impeller, and a second end to which the saidstator part of the electric motor is fixed.
 2. An electric fan accordingto claim 1, in the which the second end of the support bracket has areceptacle formed therein able to receive control circuit means coupledto the stator part of the said electric motor.
 3. An electric fanaccording to claim 2, in which the support bracket is of metal material,in particular aluminium, and is in heat exchange relationship with atleast some components of the said circuit means to encourage dissipationof heat.
 4. An electric fan according to claim 1, in which the ends ofthe said support bracket are provided with means able to allow anchorageto a supporting structure in use.
 5. An electric fan according to claim1, in which the impeller is of moulded plastics material and the magnetsof the rotor part are fixed, for example by adhesive, to a metal supportring, the said ring and the magnets being embedded in the plasticsmaterial of the impeller.
 6. An electric fan according to claim 1, inwhich the said first end of the bracket has a pin fixed to it andoperable to function as a fixed shaft, in which the impeller has a hubprovided with rotation support means rotatably mounted on the said pinor fixed shaft.
 7. An electric fan according to claim 1, in which theintermediate portion of the support bracket has a plurality of angularlyspaced deflector elements or flow straightener elements formed therein.8. An electric fan according to claim 1, in which the winding of thestat or part is formed with stacks of laminations of electricallyconductive material such as copper or its alloys, carried by a supportplate which also carries connector conductors for interconnecting them.